1. Field of the Invention
The present invention relates to an electric parking brake apparatus. More particularly, the present invention relates to an electric parking brake apparatus in which a worm shaft is formed with a first protrusion, a rotating member is formed with a second protrusion, and after the rotating member rotates by a preset rotation angle, the first protrusion of the worm shaft contacts the second protrusion of the rotating member so that the worm shaft cannot rotate any more, thereby preventing a gear jam due to over-release of the rotating member.
2. Description of the Prior Art
In general, a parking brake apparatus is used to restrain wheels so as to stop a vehicle such that it is immobilized, when a driver parks the vehicle.
Such a parking brake apparatus may be classified into a manual type in which, when a driver directly pulls a parking brake lever, a parking cable connected to the parking brake lever is pulled so that wheels are restrained, and an electric type in which, when a driver manipulates a switch, an apparatus configured with an electric motor and a gear unit pulls a parking cable so that wheels are restrained.
FIG. 1 illustrates a schematic configuration of an electric parking brake apparatus according to the related art.
As illustrated in FIG. 1, the electric parking brake apparatus according to the related art includes a parking gear 105 including a protrusion 101 protruding from a portion of an outer periphery of the parking gear, wherein a parking cable 103 is secured to a surface spaced apart from a center of the parking gear; a tension sensor 107 provided at the parking cable 103; a release switch 109 operated by the protrusion 101 to be rotated by a predetermined angle; an operation member 111 operating the parking gear 105 while being connected with the tension sensor 107 and the release switch 109; an electronic control device 113 connected with the release switch 109 and the tension sensor 107; and a parking brake switch 115 connected with the electronic control device 113 and mounted to a center fascia.
An example of operating the conventional electric parking brake apparatus having the above-described configuration will be described. When a driver turns on the parking brake switch 115 to operate the parking brake, the electronic control device 113 operates a motor 119 of the operation member 111 through the tension sensor 107, and the parking gear 105 engaged with a worm gear 121 rotates in one direction. Accordingly, the parking cable 103 is pulled, and a rear cable 125 is pulled through an equalizer 123 so that wheels are restrained.
In contrast, when the driver turns off the parking brake switch 115 or manipulates an accelerator pedal switch 117 to release the parking brake, the electronic control device 113 operates the motor 119 of the operation member 111 through the tension sensor 107, and the parking gear 105 engaged with the worm gear 121 rotates in the other direction. Accordingly, the pulled parking cable 103 is loosened, and the rear cable 125 is loosened through the equalizer 123 so that the wheels are released.
Meanwhile, when the protrusion 101 contacts the release switch 109 while the parking gear 105 rotates in the other direction, the electronic control device 113 shuts the motor 119 down such that the parking gear 105 does not rotate any more.
However, in the conventional electric parking brake apparatus having the above-described configuration, when the parking gear is over-released on account of a malfunction of the release switch, the parking brake does not operate due to a gear jam between the worm gear and the parking gear.